On a trip to Yosemite we had packed the cache with food for three of us for three days. A mama bear and her cub just went by the cache and didn't even attempt to open it. We had hung up everything else that wouldn't fit in the bag. We were so proud of the "good" hang. Mama sent the cub up and they proceeded to devour while we watched helplessly.
This is the best filter on the market. I have been using the same one for over 15 years and only replaced the filter element once. It has never clogged. Its a bit heavy but well worth the weight. It finally started to show signs of wear this year so I bought a new one. The new one has a better handle and pumps easier. And now has a pre-filter.